Magnetic junk retrieving tool



March 29, 1966 T. E. JENNINGS 3,243,218

MAGNETIC JUNK RETRIEVING TOOL Filed April 24, 1964 f v v w Z Z The/ma f. Jenn/09s l 1 l INVENTOR.

30 BY r w M W 36 L ,4 7'7'0/P/VE y United States Patent 3,243,218 MAGNETIC JUNK RETRIEVING TOOL Thelma E. .llennings, R0. Box 1904, Odessa, Tex. Filed Apr. 24, 1964, Ser. No. 362,396 6 Claims. (Cl. 294-655) This invention relates to a magnetic well tool and more particularly to a magnetic tool for use in a drilling string or the like for catching and retaining fragments of magnetic material in a well bore.

In the drilling of wells it often becomes necessary to retrieve lost objects such as fragments of broken tools or to conduct fishing operations to recover disconnected or broken sections of drilling string. Retrieving operations of this kind are carried out with various types of fishing or cutting tools attached to the lower end of a tubular string of pipe through which it is desirable to maintain fiuid circulation downwardly or upwardly, such circulation being also maintained in the annulus surrounding the string. During such retrieving operations small particles of metal are usually carried away by the circulating fluid, but larger fragments of metal may become lodged in the annulus or may settle out at locations which cause interference with the free fiow of the circulating fluid.

The present invention has for an important object the provision of a magnetic tool for use in retrieving operations of the kind referred to by which fragments of magnetic material may be retained by the tool and removed from the well bore therewith.

Another object of the invention is to provide a magnetic retrieving tool which may be readily attached to a drilling string and through which circulation of fluid may be maintained during the use of the tool.

further object of the invention is the provision in a magnetic junk retrieving tool of a permanent magnet of unitary structure which may be easily removed and replaced when necessary, and which is of strong and rugged construction.

The above objects of the invention, as well as other obvious important objects and advantages of the same, may best be understood from the following detailed explanation constituting a specification of the invention, when considered in conjunction with the annexed drawings, wherein:

FIGURE 1 is a fragmentary, vertical, central, crosssectioiral, view of a preferred embodiment of the magnetic retrieving tool of the invention; and

FIGURE 2 is a cross-sectional view, taken along the line 22 of FIGURE 1, looking in the direction indicated by the arrows.

Referring now to the drawings in greater detail the tool of the invention comprises a tubular barrel, preferably formed of paramagnetic material, such as steel, having an upper section 10 and a lower section 12, which are threadably connected together, as seen at 14.

The upper section 10 is internally threaded at its upper end for the connection thereto of the externally threaded lower end 14 of a connector member or sub 16, the upper end of the sub being provided with an externally threaded pin portion 18 whereby the tool may be connected to the lower end of a tubular string of pipe, not shown, in the usual manner.

The lower section 12 may take the form of a wash-over shoe or cutter, not shown, which may be provided at its lower end with the usual end teeth adapted for endwise milling upon rotation of tool in a well bore, or the section 12 may be of other construction, such as that shown in FIGURE 1, depending upon the operation which is to be carried out therewith. The section 12 is formed with an internal, annular, upwardly facing shoulder 2%, to

provide a lower abutment by which the magnetic element and its surrounding casing is retained in the barrel, in a manner to be more fully explained hereinafter.

The lower end of the sub 16 forms an upper abutment against which the casing of the magnetic element or core abuts when the tool is assembled.

A permanent magnetic element or core 22 is provided, which is of cylindrical shape, and which is encased in a casing or shell 24 formed of brass or other suitable nonmagnetic material.

At its lower end, the core 22 extends downwardly beyond the lower end of the casing 24 into an annular member 26, formed of paramagnetic material such as steel, having a bottom portion 28 forming a lower pole plate. The member 26 is surrounded by an. annular element 30 formed of brass or other suitable non-magnetic material, which is perforated to receive bolts 32 extending therethrough and threaded into the lower end of the casing 24 to releasably secure the element 30 to the casing. The annular element 36 is surrounded by a ring 34 of paramagnetic material, such as steel, which is formed with an external, downwardly facing shoulder 36 which rests on the shoulder 20 of the lower section 12 to support the entire unitary casing and magnetic core in place within the barrel with the upper end of the casing 24 in abut ment with the lower end of the sub 16.

Within the casing 24, an upper pole plate 38, formed of paramagnetic material, such as steel, is positioned over the upper end of the core 22.

The annular element 30 is also provided with passage ways 4%) which are disposed in communication with passageways 42 in the casing 24 so that fluid may flow freely through the string of pipe, through the sub 16 from or into the bore of the well below the tool.

The upper pole plate 38 is tightly fitted into the casing 24 and the lower pole plate 26 is tightly fitted over the lower end of the core 22, while the annular element 3% is pressed tightly on the lower pole plate element 26 and the support ring 34 fits the element 26 tightly to hold the assembly together and support the same in the barrel. The core 22 is also securely held in the casing 24 by the magnetic attraction between the core and the upper pole plate 38.

In assembling the tool the core 22 is slipped into the casing 24 where it is held by the upper pole plate 38, the lower pole plate 26 being fitted into the lower end of the core and the annular member 30 and ring 34 being pressed into place about the lower pole plate, so that the lower section 12 may be screwed onto the upper section N to complete the assembling of the tool.

Should it be necessary or desirable to remove the core and replace the same, this can be accomplished by removing the lower section 12 of the barrel, whereupon the core assembly including the casing 24, lower pole plate 26, annular member 36 and ring 34 may be removed as a unit and replaced by another such unit.

The tool of the invention possesses the advantage that the core 22 which is preferably of highly magnetizable material, which is difficult to machine and inherently brittle, is completely enclosed to protect the core against damage, while the core together with its casing forms a unitary assembly which is easily replaced when desired. It will be apparent that the core 22 and the upper and lower pole plates are securely held in a centralized position in the barrel and separated therefrom by non-magnetic material so that there is a strong magnetic field adjacent the lower end of the tool by which magnetic objects in the well bore will be held while permitting the circulation of fluid through the tool while the same is in use.

It will thus be seen that the invention constructed as described above provides a magnetic retrieving tool which (3 is of simple design and strong construction and in which the parts are readily replaced for purposes of repair.

The invention is disclosed herein in connection with a specific embodiment of the same, but it will be understood that this is intended by way of example only, and that various modifications can be made in the construction and arrangement of the parts within the spirit of the invention and the scope of the appended claims.

Having thus clearly shown and described the invention, what is claimed as new and desired to secure by Letters Patent is:

1. In a magnetic junk retrieving tool, a tubular barrel formed of magnetic material having an open end, means for connecting the other end of the barrel to the lower end of a string of pipe for rotation therewith in a well bore, a casing formed of non-magnetic material disposed in the barrel and having a central bore whose upper end is closed and a passageway outside of said bore through which fluid may flow from the string into the bore below the barrel, an upper pole plate formed of magnetic material in the upper end of said bore and a lower plate formed of magnetic material closing the lower end of said bore, and a permanent magnetic core in the casing between said pole plates.

2. In a magnetic junk retrieving tool, a tubular barrel formed of magnetic material having an open end, means for connecting the other end of the barrel to the lower end of a string of pipe for rotation therewith in a well bore, a casing formed of non-magnetic material disposed in the barrel and having a central bore whose upper end is closed, an upper pole plate in the upper end of said bore, a permanent magnetic core in the casing in contact with the upper pole plate and whose lower end portion extends beyond the lower end of the casing, a lower pole plate in the barrel surrounding and enclosing said lower end portion, an annular member formed of non-magnetic material surrounding the lower pole plate, and means for supporting said casing, lower pole plate and member in the barrel, and means forming a passageway through said casing and member in communication with the interior of said string and with said here below the barrel.

3. In a magnetic junk retrieving tool, a tubular barrel formed of magnetic material having upper and lower sections threadably connected together, means for connecting the upper end of the barrel to the lower end of a string of pipe for rotation therewith in a well bore, means forming an internal, annular, upwardly facing shoulder in said lower section, a casing formed of non-magnetic material disposed in the barrel and having a central bore whose upper end is closed, an upper pole plate of magnetic material in the upper end of said bore, a permanent magnetic core in the casing whose upper end is in contact with said upper pole plate and whose lower end extends beyond the lower end of the casing, a lower pole plate formed of magnetic material surrounding the core below the lower end of the casing, an annular member formed of non-magnetic material surrounding the lower pole plate, means for supporting the member on the casing, a support ring surrounding said member and seated on said shoulder and upon which the lower end of said casing rests to support said casing in the barrel, and means forming a passageway through the casing and member in communication with the interior of the string and with said bore below the barrel.

4. In a magnetic junk retrieving tool, a tubular barrel formed of magnetic material having upper and lower threadably connected sections, means for connecting the upper end of the barrel to the lower end of a string of pipe for rotation therewith in a well bore, means forming an internal, annular, upwardly facing shoulder in said lower section, a core of permanent magnetic material in the barrel, nonmagnetic means surrounding and extending over the upper end of the core and spacing the same inwardly from the internal surface of the barrel, magnetic means for supporting said core in said non-magnetic means, means for supporting said non-magnetic means on said shoulder, and means forming a passageway externally or" said core through which fluid may flow from the interior of said string into the bore below the barrel.

5. In a magnetic junk retrieving tool, a tubular barrel formed of magnetic material having upper and lower threadably connected sections, means for connecting the upper end of the barrel to the lower end of a string of pipe for rotation therewith in a well bore, means forming an internal, annular, upwardly facing shoulder in said lower section, a core of permanent magnetic material in the barrel, non-magnetic means surrounding and extending over the upper end of the core and spacing the same inwardly from the internal surface of the barrel, magnetic means for supporting said core in said nonmagnetic means, a pole plate formed of magnetic material on the lower end of said core, means for supporting said non-magnetic means on said shoulder, and means forming a passageway externally of said core in communication with the interior of the string and with said bore below said barrel.

6. In a magnetic junk retrieving tool, a tubular barrel formed of magnetic material having upper and lower threadably connected sections, means for connecting the upper end of the barrel to the lower end of a string of pipe for rotation therewith in a well bore, means forming an internal, annular, upwardly facing shoulder in said lower section, a core of permanent magnetic material in the barrel, non-magnetic means surrounding and extending over the upper end of the core and spacing the same inwardly from the internal surface of the barrel, magnetic means for supporting said core in said non-magnetic means, a pole plate formed of magnetic material extending below the lower end of and having an annular portion surrounding the lower end portion of the core, means for supporting said non-magnetic means on said shoulder including non-magnetic means positioned to space said pole plate from the internal surface of tile barrel, and means forming a passageway externally of said core in communication with the interior of said string and with said bore below said barrel.

References Qited by the Examiner UNITED STATES PATENTS 2,734,767 2/1956 Donham 294-655 FOREIGN PATENTS 753,458 7/1956 Great Britain.

GERALD M. FORLENZA, Primary Examiner.

G. F. ABRAHAM, Assistant Examiner. 

1. IN A MAGNETIC JUNK RETRIEVING TOOL, A TUBULAR BARREL FORMED OF MAGNETIC MATERIAL HAVING AN OPEN END, MEANS FOR CONNECTING THE OTHER END OF THE BARREL TO THE LOWER END OF A STRING OF PIPE FOR ROTATION THEREWITH IN A WELL BORE, CASING FORMED OF NON-MAGNETIC MATERIAL DISPOSED IN THE BARREL AND HAVING A CENTRAL BORE WHOSE UPPER END IS CLOSED AND A PASSAGEWAY OUTSIDE OF SAID BORE THROUGH WHICH FLUID MAY FLOW FROM THE STRING INTO THE BORE BELOW THE BARREL, AN UPPER POLE PLATE FORMED OF MAGNETIC MATERIAL IN THE UPPER END OF SAID BORE AND A LOWER PLATE FORMED OF MAGNETIC MATERIAL CLOSING THE LOWER END OF SAID BORE, AND A PERMANENT MAGNETIC CORE IN THE CASING BETWEEN SAID POLE PLATES. 